CMSPermGenSweepingEnabled

So the final answer is “it depends”
I would still recommend not to use intern in the common application though there are few edge cases where it would make sense.

I’ve checked on both IBM Java5 and IBM Java6.
Both loop and multi-lines concatenations turn into a StringBuilder.
Seems like there are less and less reasons to micro tune your code.
Thanks.

————————————————
concatenating in a loop – Javap will show you StringBuilder
————————————————
public static volatile String s = “”;
public static void main(String[] args) throws InterruptedException {
for (int i=0; i<10; i++) {
String strOfThisCycle = String.valueOf(i);
s += strOfThisCycle;
}
}

————————————————
Concatenating over multiple lines – Javap will show you StringBuilder
————————————————
public static void main(String[] args) throws InterruptedException {
String strOfThisCycle = “0″;
s += strOfThisCycle;
strOfThisCycle = String.valueOf(System.currentTimeMillis());
s += strOfThisCycle;
}

In java 6 I think that if you run javap on the for loop example you will
see that it uses StringBuilder also, But I might be mistaken

Eyal

You could just have it enabled on the IBM JVM and not enabled in the Sun JVM (50% benifith with 1% work).

If on Sun the GC log is printed to the standard error, you could re-direct it (linux assumed) to Apache’s rotatelogs utility.
http://httpd.apache.org/docs/2.0/programs/rotatelogs.html
Just an idea.

Good luck on that.